Quest for a perfect bicycle - Batavus Champion frame alignment

A common problem on a steel vintage racer is a lack of frame alignment. There are a few factors that cause this issue, but basically a major one is rear fork alignment. As a result of bad rear fork alignment bicycle may have a problem with handling, uneven tires wear, loss of driving energy.

For fixing this issue, we needed: string, ruler, two old rear wheel axle and a peace of wood as a leverage.

You can closely see on the drawing below what was the problem with Batavus rear fork. The wheels are in red. The rear wheel is out of alignment with the rest of bicycle.

 

 First we stretched a string from one rear drop, crossing head tube, and backed to other rear drop. Then we measured a distance from seat tube to each side of a string - if there is a difference bigger than 1 mm, bicycle can have driving issues.

After making a measurements, rear fork on Batavus bicycle was 5 mm tilted to right.

On the next picture you can see how the process of bending a rear fork works. We were doing it in small increments, patiently, aiming to get a perfect position as much as we could. 

After string measurements showed satisfying results, it was time to check and correct rear drops alignment.

...and after a couple of hours, the result was straight frame :-)